JPH0329349A - Material for ceramic substrate - Google Patents

Abstract

PURPOSE:To execute a sintering operation in the air or in a reducing atmosphere at 850 to 950 deg.C and to enhance an acid-resistant property and an alkali- resistant property by a method wherein a raw-material powder composed of a specific inorganic powder and of a glass powder containing ZrO2 is sintered. CONSTITUTION:A mixture composed of the following is sintered: 20 to 65wt.% of at least one kind of inorganic powder which is selected from a group of an alumina powder, a mullite powder, a quartz powder and a cordierite powder; 80 to 35wt.% of a glass powder containing ZrO2, or preferably a glass powder whose main components are SiO2, Al2O3, B2O3, MgO, CaO, BaO and ZrO2. That is to say, a glass composition such as the alumina powder, the mullite powder or the like whose sintering property is high and whose acid-resistant property after a sintering operation becomes high is used. Thereby, it is possible to obtain a dense ceramic substrate which can be sintered at a low temperature of about 900 deg.C and whose acid-resistant property and alkali-resistant property have been enhanced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a low-temperature fired ceramic multilayer substrate material for mounting a high-speed LSI.

[Prior Art] In recent years, in accordance with the demand for miniaturization of electronic devices, Ic,
2. Description of the Related Art The degree of integration of semiconductor devices such as LSIs is increasing, and devices are becoming smaller. Along with this, it has become important to downsize and increase the density of substrates on which elements are mounted, in terms of downsizing and speeding up the overall system.

Conventionally, a mounting board that has been generally used as a highly reliable board capable of high-density wiring has been a multilayer board made of 90 to 96% alumina ceramics as an insulating material. However, this alumina multilayer substrate has a drawback that the capacitance between wirings becomes large due to its high dielectric constant, resulting in a long signal propagation delay time. Furthermore, since the firing temperature of alumina multilayer boards is high, it is necessary to use high-melting point metals such as Ws No.
This not only becomes an obstacle to increasing density, but also poses a problem in reducing signal propagation delay time.

Therefore, in order to solve the above problems, it has been proposed to construct a multilayer substrate using a glass-alumina composite ceramic made by adding alumina to low-melting glass in place of the alumina substrate. This glass-alumina composite ceramic multilayer substrate (hereinafter referred to as a low-temperature fired multilayer substrate) has an alumina filler dispersed in a glass matrix, and is densified by viscous sintering of the glass. Therefore, it becomes possible to bake at a low temperature of 850° C. to 950° C., and a low resistance conductor (Au, Ags Cu, etc.) can be used as a wiring conductor. Furthermore, since the glass component is increased, the inductivity of the substrate is reduced, and as a result, the signal transmission delay time is shortened, resulting in a mounting board compatible with high-speed devices.

Among these low-temperature-fired multilayer substrates, substrates that use Cu as a conductor material (hereinafter referred to as copper conductor ceramic substrates) not only satisfy all of the above characteristics, but also have good wiring conductor characteristics, and especially It has excellent solderability, migration, signal transmission characteristics, etc.

Here, the process for producing this copper conductor ceramic substrate will be explained. The raw materials are glass powder and alumina powder with controlled particle sizes, and organic binders, plasticizers, dispersants, organic solvents, etc. are added to these powders for molding. The mixture is mixed using a ball mill for 24 to 48 hours until it becomes a slurry, and then this is formed into a sheet on an organic film using a doctor blade method to prepare a green sheet. The green sheet that has been peeled off from the organic film is cut into desired dimensions, through-holes are formed using drills or pins, copper paste is filled into the through-holes, and then copper paste is printed on at least one of the top and bottom surfaces. , forming an in-plane wiring pattern. Next, stack the required number of these printed green sheets and heat them at a temperature of 80°C to 150°C.
It is integrated by lamination pressing under a pressure of 120 kg4 to 250 kg4, and contains at least one of water vapor, hydrogen, and a trace amount of oxygen. It is fired in a nitrogen atmosphere, and finally, plating, pin brazing, etc. are performed as necessary. In addition, copper polyimide may be formed on the surface to form one layer of high-density wiring. This copper polyimide is made by forming a fine pattern of copper by photolithography and using photosensitive polyimide as an interlayer insulating film, thereby making it possible to replace the substrate with high density and high reliability. However, since the copper polyimide process requires various surface treatments, the substrate material is required to have acid resistance and alkali resistance.

The characteristics and process of low-temperature fired multilayer substrates, particularly copper conductor ceramic substrates, have been explained above, and now the glass materials conventionally used will be explained.

Glass materials can be broadly classified from the point of view of the wiring conductors formed therein: S102-8203-PbO-R, which includes pbo for Aus Ags^g-Pd conductors that can be fired in the atmosphere;
Sl02-820s series, 8102-t for O (where R is a metal element of group ■ or group II) glass and Cu conductor that requires firing in a neutral or reducing atmosphere
hi3-A1203-R゜0 (where R゜ is an alkaline earth element) system, sto2-8203-A120
There are various types such as 3-R'O-ZnO glass.

The S102-B20 3-PbO-RO glass is typified by the system shown in Japanese Patent Publication No. 60-8229, and contains 5 to 90% by weight of aluminum oxide and 1 to 90% by weight of lead oxide in terms of ceramic oxides. 40% by weight, boron oxide 1 to 30% by weight, silicon dioxide 2 to BO by weight, group Ⅰ element oxides 0.05 to 25% by weight, group Ⅰ elements (with the exception of carbon,
The composition is selected to have a total ffi of 100% by weight in a composition range of 0.01 to 10% by weight of oxides (excluding silicon and lead). With the ceramic composition shown here, a high-density wiring board with a green sheet laminate can be replaced at a temperature of 1400° C. or lower. However, although this ceramic is suitable for firing in the air to make uSAg and Ag-Pd wiring conductors, it is not suitable for firing in a reducing atmosphere such as Cu or Nl because it essentially contains PbO. However, a problem arises in that a reduction reaction of PbO occurs and metal PB precipitates, which deteriorates the insulation properties of the ceramic layer. Furthermore, since PbO is harmful to the human body, it causes environmental problems such as powder treatment during cutting, making it difficult to use as a substrate.

Further, the glass material of 9102-B203 is AI203 as described in Japanese Patent Application Laid-open No. 59-995.
, 8102, B203, Na20, K20, CaO
It is composed of oxides such as SLIO, and its composition is that of glass ceramic: A1203: 50.5% by weight
, 3102: 35.0 weight,%, B203:
13.0% by weight, Na20: 0.75% by weight, K
20: 0.70ffiffi%, CaO: 0.
15% by weight, LjO: 0.15% by weight.

Glass with this composition has a small coefficient of thermal expansion and good chemical durability, so it is suitable for use in spaces where silicon elements are directly mounted. However, since it essentially contains an alkali element, when used as a substrate material, the alkali component may cause electromigration if high pressure is applied in a high humidity atmosphere.

Furthermore, the SiO2-B20 s-^1203-R
“0-series glass material has a glass composition of 8102:30-50 as stated in Japanese Patent Application Laid-Open No. 62-292654.
Weight%, B203: 30-50% by weight, A1203
: 5 to 15% by weight; R'OCR' is an alkaline earth element): 5 to 25% by weight. Although this glass material can be mixed with cordierite powder and sintered at temperatures below 100° C., it does not necessarily have sufficient chemical stability (acid resistance and alkali resistance) because it contains a large amount of B203 components. Although the chemical stability is improved by adding Al203, there is a limit to its effect because adding 15% by weight or more of A1203 increases the glass softening temperature and affects sinterability. Therefore, in order to further increase its chemical stability, ZnO was added thereto to form SiOz-B203-AI203-R'O-Z.
There is one made of nO-based glass material. This is an SiO
2: 48-56% by weight, AI21) 3: 12-1
8wt 2%, B203: 8-19wt%, MgO
: 1 to 10% by weight, CaO: 2 to 8% by weight, SrO
Alternatively, a glass material having a composition of BaO: 2 to 9% by weight and ZnO: 1 to 9% by weight can be mixed with alumina powder and sintered at 1000° C. or lower, and has improved acid resistance.

However, as the packaging density becomes higher, the wiring width/wiring spacing of the low-temperature-fired multilayer ceramic board using the green sheet stacking six-layer method becomes insufficient, so copper polyimide using photolithography is used as a low-temperature-fired multilayer ceramic board. It is necessary to form it on a ceramic substrate. This copper polyimide is
The formation process is explained on pages 29-34 of the Institute of Electronics and Communication Engineers journal CPM86-63, which involves forming a copper conductor by plating and forming an insulating layer by photosensitive polyimide.
At that time, strong acid or strong alkali treatment is required as surface treatment. For strong acid and strong alkali treatments, the substrate is exposed to about 5% H
Cj 9 in NaOH at a temperature of 80-80 °C, 30
This is done by soaking for ~150 minutes. Therefore, the above-mentioned 8102-8203-A1203 with improved acid resistance
- Even with R'O-ZnO glass materials, glass components may be eluted into the processing solution during strong acid or strong alkali treatment, resulting in a decrease in metallization strength and glass ceramic strength, and poor conductivity between wiring. There is.

[Problems to be solved by the invention] Conventional glass materials for low-temperature firing substrates are structured in this way, so glass containing a large amount of PbO has good acid resistance, but increases the dielectric constant of the substrate, causes environmental problems, etc. There is a problem with
Furthermore, there is a concern about electromigration with glass containing alkaline components.

Furthermore, 8102-8203-A1203-R'
0 series and SiO2-B20s-A1203-
R'0-ZnO glass has problems such as a large amount of glass elution during acid/alkali treatment in the copper polyimide process, resulting in wiring short circuits and a decrease in substrate strength.

The present invention was made to solve the above-mentioned problems. The purpose of the present invention is to provide a glass-based material that can be sintered even in an atmosphere containing wet hydrogen, and that can be used to fabricate a low-temperature firing multilayer substrate with excellent acid and alkali resistance.

[Means for Solving the Problems] The ceramic substrate material of the present invention contains 20 to 65% by weight of at least one kind of inorganic powder selected from the group consisting of alumina powder, mullite powder, quartz powder, and cordierite powder, and ZrO2. glass powder containing, preferably 810
2, N203, B20s, MgOsCaOs
Glass powder containing BaO, ZrO2 as main components 80~
This is a ceramic substrate material obtained by sintering a mixture consisting of 35% by weight.

[Function] The ceramic substrate material of the present invention is obtained by sintering the raw material powder consisting of the above-mentioned specific inorganic powder and the above-mentioned glass powder containing z'02. Sintering at 850-950°C is possible, and acid resistance is significantly improved.

[Example] As the glass powder containing ZrO2 used in the present invention, 8
With 102 as the basic constituent, the composition is PbO-free, alkali-free, and contains 8203, and by selecting the mixing ratio of alumina and alkali metal oxide and adding ZrO2, low-temperature sinterability and acid resistance are improved. Preferably.

That is, the main components of the preferable glass required in the present invention are S 1 02, M
20s, B20s, MgO, CaO, B
It is composed of aO% ZrO2. The preferable composition range of the glass is 49 to 56% by weight of 8102.
, N203 is 9-20% by weight, B203 is 10-15% by weight, CaO is 3-8% by weight, BaO is 3-8% by weight,
It is desirable that MgO be 5 to 15% by weight and z'02 be 1 to 6% by weight.

In this composition, if sto2 is less than this range, acid resistance tends to deteriorate, and if it exceeds this range, sinterability tends to deteriorate. Furthermore, if the N203 content is less than this range, the acid resistance deteriorates and at the same time phase separation tends to occur easily, while if it exceeds the content, the sinterability tends to deteriorate. B203
If the amount is less than this range, the sinterability tends to be poor, and if it is more than this range, the acid resistance tends to be poor. The more BaO there is, the better the sinterability becomes, but if it exceeds the above range, the acid resistance tends to deteriorate. Zr○2 is effective in improving acid resistance, but if it exceeds this range, acid resistance tends to deteriorate.

The above-mentioned glass powder is used as a raw material powder in the above-mentioned specific blending ratio together with one type of refractory inorganic powder selected from the group consisting of alumina powder, mullite powder, quartz powder, and cordierite powder. After the sheet is shaped, it is sintered at 850 to 950°C to obtain a highly acid-resistant ceramic substrate.

The effect of the glass component in the present invention is 8102, B20
s, ZrO2 network formation, B203
Low-temperature sinterability is achieved by MgO, CaO, and BaO, and acid resistance is improved by Af20s and Zr○2. That is, for example, the MgO-CaO-B20s system or P2 described in JP-A-62-128981
05 - S1 like Nl203-S102 glass
Acid resistance is improved by replacing a part of the glass, which was previously composed of 02, M203, B203, MgO 2 and CaO, with BaO and ZrO2. As will be described later, FIG. 1 is a graph showing an example of the improvement in acid resistance.
2: 52, N20s: 13, CaO: 5, B20
3:13, BaO: 5, MgO: 10-xs
ZrO2: Using glass powder with a composition of x (xi, 2, 4, all numbers are weight%), alumina powder and 1:
Acid resistance (5% HCf
, weight loss per unit area when immersed in an 80°C aqueous solution for 0 to 120 minutes. In FIG. 1, x-0 (a) is a conventional example, and x-2 (x-2) and 4 (C) are embodiments 1 and 2 of the present invention, respectively, which will be described later. As a result of acid resistance, xi
It is clear that item (C) is the most effective, but compared to the acid resistance of glass for bashivation, there is no problem with the acid resistance of <<b>> and (C) in FIG.

Examples of the substrate material of the present invention will be described below.

Example I SI02: 52, AJ20s: 13, Cab:
5, B203:13, Bad: 5, MgO:
10. A glass assembly containing ZrO2:2 (weight ratio) was produced. Powder obtained by crushing this glass and alumina powder were mixed in a weight ratio of 1:1, and isobutyl methacrylate resin, dibutyl phthalate, and triolein were mixed in a weight ratio of 9:4:1 to 100 parts of the mixed powder. A slurry was prepared by mixing isobutyl acetate as a solvent at a weight ratio of 50 to 7. This slurry was degassed until it reached an appropriate viscosity, and then molded with a doctor blade to a thickness of 0.2
0-0.25 Ceramic green sheets of the same size were prepared. Cut this green sheet into 50aa + square pieces,
The sheets were laminated and pressed and fired at 900'C in N2 in a ¥1''! closed atmosphere furnace.The temperature increase rate was 5°C/win, and the binder was removed when the sample temperature was 250 to 820'C. The test was carried out by changing the atmosphere to wet nitrogen having a dew point of 70° C. or higher.

In this way, the sintered ceramic substrate was placed in a hydrochloric acid aqueous solution (5%) at 60°C for X minutes (x=30, 80, 9
0 and 120) The amount of glass eluted from the ceramic substrate surface with respect to the immersion time was measured. The results are shown in Fig. 1 (mountain). The horizontal axis is time (minutes) and the vertical axis is glass elution m (mg/cj) per unit area.
I did it minute by minute. The amount of elution was only 0.21 mg/cj even after immersion for 120 minutes, which was at a level sufficient to allow use as a ceramic substrate for mounting electronic components that requires acid treatment such as plating.

Comparative Example 1 Glass composition: S102:52, #203:1
3, Cab: 5, B203: 13, MgO: 10 glass was produced, and a substrate was produced in the same manner as in Example 1,
Acid resistance was determined as II. The results are shown in (a) in FIG.

Example 2 Glass composition: SI02: 52, /V203:1
3, CaO: 5, B203: 13, MgO: [i
, ZrO2:4 glass was produced, a ceramic substrate was produced in the same manner as in Example 1, and its acid resistance was evaluated. In FIG. 1, the M1 constant result of the amount of glass eluted from the ceramic substrate with respect to that time is shown in (C).

It is clear from FIG. 1 that the acid resistance improves as the ZrO2 component increases. However, when the shrinkage rate and water absorption rate of the ceramic substrates of Examples 1 and 2 were measured, Zr
The shrinkage rate and water absorption rate of the substrate of Comparative Example 1 with 0 O2 component ((mi) in Figure 1) and the substrate of Example 1 with 2% by weight (Nakayama in Figure 1) are both 13.0±0. 2% and 0%, but the substrate of Example 2 (first
In <<C>>) in the figure, 11oO±0.4% and 0.02
%Met. This is because ZrO2 has four layers. This shows that the sintering conditions are not necessarily sufficient when using a certain amount of glass.

Figure 2 shows the relationship between the viscosity and temperature of the glass used for the substrates with ZrO2 components of 0, 2, and 4, that is, Comparative Example 1 (a), Example 1 (Mount), and Example 2 (C). . (Small indicates the glass softening viscosity (lower limit). From Figure 2, it can be seen that for glasses containing 0 and 2% by weight of the 02 component ((a) and <C) in Figure 2), the viscosity at 900°C (log η) is 6 or more, but for 2% by weight glass (<b> in Fig. 2),
It can be seen that the value is 5.6. Note that the unit of η is Boaz. In general, sintering when the glass content is large is caused by viscous sintering of the glass due to a decrease in glass viscosity at high temperatures.
This often affects the shrinkage rate and porosity. Therefore, when using a glass material with a ZrO2 component of 4 weight 96, it is necessary to sinter it at a temperature at which the viscosity (log η) becomes 6 or less, that is, 920° C. or higher, as shown in FIG.

Next, alkali resistance was evaluated in the same manner as acid resistance.

Alkali resistance was tested in a 2% N'a OH aqueous solution at 60°C. The results are shown in FIG. From Figure 3, 1
Even when immersed in a 2% NaOH aqueous solution at 60°C for 20 minutes, the heavy GM of Comparative Example 1, Example 1, and Example 2 was all 0.05 IIlg/cJ or less, and z'02
Good results were obtained for all glasses containing 0, 2, and 4% by weight.

Example 3 In Example 1, alumina powder was used as the ceramic filler, but here mullite powder was used, and a ceramic substrate was produced using the same materials and process as in Example 1 except for the use of mullite powder. Even when using mullite, the sinterability is
The shrinkage rate and porosity were 12.9±0.02% and θ%, which were almost the same as those of alumina.

Note that the acid resistance of mullite itself was lower than that of alumina, so the acid resistance slightly decreased, but it was still sufficient to withstand use as a substrate. Furthermore, since the dielectric constant of mullite is smaller than that of alumina, the dielectric constant of the glass ceramic substrate itself is 6.0 to 6.0 compared to that of alumina glass.
5, compared to 5.0 to 5.0 for mullite-glass systems.
It is possible to make it as small as 5. Therefore, in the future where high-speed signal transmission is required and substrates with low dielectric constants are desired, mullite-glass ceramic substrates will become important.

[Effects of the Invention] As described above, the present invention uses a specific glass composition that has high sinterability with alumina powder or mullite powder and has high acid resistance after sintering. A dense ceramic substrate that can be sintered at low temperatures and has high acid and alkali resistance can be created.

[Brief explanation of drawings]

Figure 1 is a graph showing the effect of the ZrO2 component on the acid resistance of a substrate using the ceramic substrate material of the present invention;
The figure is a graph showing the relationship between viscosity and temperature of the glass material for ceramic substrate material of the present invention, and Figure 3 is a graph showing the effect of Zr on the alkali resistance of the substrate using the ceramic substrate material of the present invention.
It is a graph showing the effect of O2 component. Agent large {Gomasuojin twice Temperature (°C) (minutes)

Claims (1)

[Claims] (1) At least one selected from the group consisting of alumina powder, mullite powder, quartz powder, and cordierite powder
A ceramic substrate material, which is a mixture of at least one inorganic powder and a glass powder containing ZrO_2, which is obtained by sintering a mixture consisting of 20 to 65% by weight of the inorganic powder and 80 to 35% by weight of the glass powder. .